HP OpenVMS Systems Documentation

HP OpenVMS Alpha Version 7.3--2 Release Notes

Previously, the linker's check between the library and the shareable
image was too sensitive. It compared against the exact date and time,
signaling LINK-I-DATMISMCH, if no match was found. Now, however, it
makes only the same check that the image activator does: that is, it
uses the GSMATCH criteria to verify compatibility.

The old behavior (check for date and time) can be obtained by setting
the logical name LINK$SHR_DATE_CHECK.

In releases prior to OpenVMS Version 6.1, LTDRIVER did not set the
"extended DDT" bit; therefore, the POSIX function CANCEL SELECTIVE did
not work with LTDRIVER. This problem has been corrected, but a
restriction remains.

Although this fix allows $QIO reads and writes to be selectively
canceled, any $QIO done to the port driver (that is, with the
IO$_TTY_PORT function modifier --- such as a LAT connect $QIO)
cannot be canceled with CANCEL SELECTIVE.

OpenVMS callable mail routines are not thread-safe. Refer to
the Guide to the POSIX Threads Library for more information about calling non-thread-safe
routines within a threaded application.

Because callable mail context information is maintained on a
per-process (rather than a per-thread) basis, multiple threads
performing context-based processing must be synchronized so that only
one mail context of a given type is active at once. Otherwise,
one thread could corrupt another thread's mail operations.

On OpenVMS Alpha systems, there is an additional restriction when
kernel threads is enabled in a multithreaded environment. In this
environment, callable mail should be used only in the initial thread.

INTS.H In some prior releases of OpenVMS, the POSIX Threads C
language header file PTHREAD_EXCEPTION.H inadvertently contained a
#include of the C header file INTS.H. This has been corrected in
OpenVMS Version 7.3-2. PTHREAD_EXCEPTION.H no longer causes INTS.H to
be included in a compilation. There may be some applications whose
compilation requires the presence of INTS.H and which are erroneously
relying on PTHREAD_EXCEPTION.H to provide it. Recompiling such
application source modules on an OpenVMS Version 7.3-2 system will
result in diagnostic messages from the C compiler. These messages
identify symbols or data types (for example, int32) that originate in
INTS.H and are undefined. To correct such application source modules,
add a direct #include of
<ints.h>
before the first use of the corresponding symbols or types.

timespec_t
typedef In prior releases of OpenVMS, the POSIX Threads C language
header file PTHREAD.H contained a definition for a typedef named
timespec_t
. This is a nonstandard symbol, which does not belong in PTHREAD.H.
(This typedef was present for historic reasons related to the contents
of C RTL header files such as TIME.H and TIMERS.H.) For OpenVMS Version
7.3-2, the standards compliance of the C RTL and threads header files
has been improved. As a result, PTHREAD.H no longer provides the
timespec_t
typedef. There may be some applications whose compilations require
the
timespec_t
typedef, and which erroneously rely on PTHREAD.H to provide it---either
directly or indirectly (for example, by using TIS.H). If such an
application source module is recompiled on an OpenVMS Version 7.3-2
system, you may get C compiler diagnostic messages listing
timespec_t
as an unknown symbol or type. To correct such application source
modules, either replace the uses of
timespec_t
with structure
timespec
, or include the C RTL header file TIMERS.H before the first use of the
timespec_t
symbol. If your application build environment uses a private copy
of any older C RTL or threads header files or an extract of them that
includes the
timespec
structure or the
timespec_t
typedef (both of which are not recommended), you may see an additional
compilation error. The compiler may display messages stating that the
timespec
structure is redefined or defined twice. In such a case, revert to
using the system-supplied C RTL and threads header files, or replace
the private extracts involving the
timespec
structure with an inclusion of the system-supplied TIME.H header file.

As of OpenVMS Version 7.3-2, the adaptive thread scheduling behavior
that is described in the Guide to the POSIX Threads Library has been implemented with a new
priority adjustment algorithm. In some cases, the new algorithm should
help avoid problems that can arise when throughput-policy threads of
different priorities share synchronization objects. Priority adjustment
can also improve application throughput and overall system utilization.
Priority adjustment of threads with throughput scheduling policy is
automatic and transparent.

If the POSIX Threads Library detects an uncorrectable serious problem
at run time (such as data structures that have been damaged by data
corruption somewhere in the application), the library may terminate the
running image. During termination, the library may trigger creation of
a process dump file (which can subsequently be used to diagnose the
failure, by way of ANALYZE/PROCESS_DUMP). The size of such a process
dump file depends on the size of the process's address space at the
time of the failure and can be quite large.

Starting in OpenVMS Version 7.3, the POSIX Threads Library is sensitive
to dynamic changes in the number of CPUs that are configured for a
running multiprocessor Alpha system. When use of multiple kernel
threads is enabled (by way of the LINK/THREADS_ENABLE qualifier or the
THREADCP command verb) for an image, the POSIX Threads Library monitors
the apparent parallelism of an application and creates multiple kernel
threads up to the number of CPUs available. Each kernel thread can be
scheduled by the OpenVMS executive to execute on a separate CPU and,
therefore, can execute simultaneously.

While an application is running, an operator can stop or start a CPU.
Such a dynamic change affects the allowable number of kernel threads
that future image activations can create. It also will now affect
images that are currently executing.

When a CPU is added or removed, the threads library will query for the
new number of active CPUs, and compare this to the number of kernel
threads that the process is currently using. If there are now more CPUs
than kernel threads, the library will try to spread out the existing
POSIX threads over the CPUs (creating new kernel threads as needed, now
or in the future). If there are now fewer CPUs than kernel threads, the
library will force the extra kernel threads to hibernate, and will
reschedule the POSIX threads onto the remaining kernel threads. This
will ensure that --- so far as the process is concerned --- there will
not be more kernel threads competing for CPU resources than are
available.

The POSIX Threads Library provides enhanced data collection
capabilities to support monitoring and debugging tools. These
capabilities provide support for Visual Threads, a new debugging and
analysis tool for threaded programs on OpenVMS Alpha systems. Visual
Threads, which is licensed with OpenVMS Version 7.3, provides
monitoring, automatic debugging, and performance evaluation of
multithreaded applications.

The method used for attaching a security profile to an I/O Request
Packet (IRP) changed with Version 7.2.

In versions of OpenVMS prior to Version 7.2, the IRP structure
contained the address of the processwide Access Rights Block (ARB)
security structure of the requestor. Beginning with OpenVMS Alpha
Version 7.2, the address of the new security profile structure (Persona
Security Block, or PSB) was added to the IRP as a functional
replacement of the ARB address.

The I/O subsystem maintains its access to the PSB through a reference
counter within the PSB. The I/O subsystem increments this reference
counter at the time of IRP creation and decrements the counter at I/O
postprocessing of that IRP. When this counter reaches zero, the PSB
structure is deallocated.

Device drivers that create or clone copies of IRPs to facilitate
multiple I/O operations per request, and subsequently pass the copies
to the I/O subsystem for postprocessing, must make code changes to
account for the extra references to the PSB in these additional IRPs.
This is done by passing the PSB address located in the copied IRP to
the NSA_STD$REFERENCE_PSB routine. The include file and routine call
for NSA_STD$REFERENCE_PSB is as follows:

#include <security-macros.h>
/* Increment REFCNT of PSB that is now shared by both IRPs */
nsa_std$reference_psb( irp->irp$ar_psb );

Device drivers need to make this change under the following conditions:

If a device driver creates a new IRP by duplicating an existing IRP
and submits both the original and the duplicate IRPs for I/O
postprocessing by calling IOC_STD$SIMREQCOM or IOC_STD$DIRPOST1, the
device driver must call NSA_STD$REFERENCE_PSB sometime after
duplicating the IRP, but before submitting it for I/O postprocessing.

If a device driver creates a new IRP by duplicating an existing IRP
and does not put the address of some procedure descriptor into the
IRP$L_PID cell in either the copy or the original IRP, and the device
driver submits both the original and the duplicate IRPs for I/O
postprocessing by calling IOC_STD$REQCOM, COM_STD$POST,
COM_STD$POST_NOCNT, or IOC_STD$POST_IRP, the device driver must call
NSA_STD$REFERENCE_PSB sometime after duplicating the IRP but before
submitting it for I/O postprocessing. Device drivers that perform
these steps are also likely to put the address of some procedure
descriptor into IRP$L_PID. Therefore, most device drivers that
duplicate IRPs should be able to function correctly on OpenVMS Version
7.2 or higher without making source changes, relinking, or recompiling.

Failure to call NSA_STD$REFERENCE_PSB in these circumstances will
result in corrupt tracking information within the PSB, which can result
in system failures.

If you make code changes in a device driver to call
NSA_STD$REFERENCE_PSB, you must recompile and relink the driver to run
on OpenVMS Version 7.2 or higher.

Several routines are used by privileged code to create OpenVMS fork
execution threads. These routines run in system context independent of
any process. There are four variations of these routines, depending on
whether an immediate or queued fork is required and on which language
interface is being used:

EXE$QUEUE_FORK

EXE_STD$QUEUE_FORK

EXE$PRIMITIVE_FORK

EXE_STD$PRIMITIVE_FORK

These routines must be called at or above IPL$_RESCHED, to prevent
accidental rescheduling to a different CPU during their execution. Such
a reschedule could cause the system to hang.

In OpenVMS V7.3-1, if SYSTEM_CHECK is set to 1, these routines check
the system IPL at entry. If the IPL is below IPL$_RESCHED, the system
will fail with an SPLINVIPL bugcheck.

For performance reasons, the IPL is not verified if SYSTEM_CHECK is set
to zero (the default). Incorrect code may cause the system to hang if a
reschedule to another CPU occurs during execution of these routines
from process context (for example, below IPL$_RESCHED).

In the OpenVMS RTL Library (LIB$) Manual, there is an error in the description of the flags
argument to LIB$FIND_IMAGE_SYMBOL. Flags is documented as passed by
reference. This is incorrect and returns an error message,
LIB-F-INVARG, as a return value. If flags is passed by value,
LIB$FIND_IMAGE_SYMBOL works as expected.

This error will be corrected in the next revision of the OpenVMS RTL Library (LIB$) Manual.

LIB$FIND_IMAGE_SYMBOL may signal a warning (LIB$_EOMWARN) to indicate
that the image being activated contains modules that had compilation
warnings. A condition handler used with LIB$FIND_IMAGE_SYMBOL should
probably handle this as a special case.

To allow LIB$FIND_IMAGE_SYMBOL to continue execution after signaling
LIB$_EOMWARN, the condition handler should exit with SS$_CONTINUE. For
this reason, you may choose not to use LIB$SIG_TO_RET as a condition
handler for LIB$FIND_IMAGE_SYMBOL.

The following information should be added to topics in the reference
section at the end of the OpenVMS RTL Screen Management (SMG$) Manual:

V7.2

The following statement should be added to the Condition Values
Returned section of routine SMG$DELETE_VIRTUAL_DISPLAY: "Any
condition value returned by the $DELPRC system service."

The description of routine SMG$GET_TERM_DATA contains an error in
the Arguments section for the capability-data
argument. The correction is as follows:

access:

write-only

mechanism:

by reference, array reference

The description of routine SMG$SET_OUT_OF_BAND_ASTS contains an
error in the Arguments section for the AST-argument
argument. The symbolic names in the Data Structure diagram are
incorrect. The symbolic names in the paragraph under this diagram are
correct. The correct and incorrect symbolic names are as follows:

Incorrect

Correct

SMG$L_PASTEBOARD_ID

SMG$L_PBD_ID

SMG$L_ARG

SMG$L_USER_ARG

SMG$B_CHARACTER

SMG$B_CHAR

V7.1

In the documentation for the SMG$READ_COMPOSED_LINE routine, the
following text should be appended to the description of the
flags argument: "The terminal characteristic
/LINE_EDITING should be set for your terminal for these flags to work
as expected. /LINE_EDITING is the default."

The description of routine SMG$SET_KEYPAD_MODE should contain this
note:

Note

Changing the keypad mode changes the physical terminal setting. This is
a global change for all virtual keyboards, not just the virtual
keyboard specified by the keyboard-id argument.

The version of SORT32 that shipped with OpenVMS Alpha Versions 7.3 and
7.3-1 did not properly write VFC information to VFC output files when
specification files were used. This problem has been corrected.

SORT32 does not always delete temporary work files. It's a good idea to
periodically check SYS$SCRATCH or wherever you put SORT32 work files to
see if any undeleted work files can be deleted to free up disk space.

SORT32 and Hypersort use different sorting and work file algorithms.
Either sort utility may be faster depending on the input file and the
memory/disk/CPU configuration. Make sure that working set extent is at
most one third of page file quota with either SORT32 or Hypersort.

SORT32 and Hypersort allocate fixed-sized slots for sort work files
based on the longest record length (LRL) information in the file. To
improve sort performance, try to set LRL information in the file as
close as possible to the actual longest record length. Poor initial
performance may be the result of sorting some files produced by C
programs, because the LRL is set higher than needed (to 32767).

The functional changes to SYS$ACM[W] described in this section are
introduced in OpenVMS Version 7.3-2. In these descriptions,
nonprivileged processes refer to processes running in
user mode that do not have SECURITY privilege.

Timeout processing Timeout processing is now enforced for
nonprivileged processes. Other processes can request timeout processing
by specifying the ACME$M_TIMEOUT function modifier.

Dialogue mode iteration limit Nonprivileged processes are now
limited in the number of iterative requests they can make in a dialogue
sequence of calls.

Logon type restriction The following ACME$_LOGON_TYPE item code
values are reserved for use by LOGINOUT:

ACME$K_BATCH
Zero (0)

You also no longer need IMPERSONATE privilege to specify the
ACME$_LOGON_TYPE item code.

Refer to the SYS$ACM[W] system service description in HP OpenVMS System Services Reference Manual for
more details.

Management of Timer Queue Entries was redesigned for OpenVMS Alpha
Version 7.3-1 to provide significantly higher performance for systems
using many TQEs. This change is transparent to nonprivileged
applications.

Privileged code can no longer manipulate TQEs directly in any form. In
particular, directly accessing pointers in the TQE's queue header
(TQE$L_TQFL/TQE$L_TQBL) causes an access violation in almost all cases.
Privileged code may continue to use the internal routines
exe_std$instimq/exe$instimq and exe_std$rmvtimq/exe$rmvtimq to enter or
remove Timer Queue Entries.